How does one call a class if one gets the class name from a database?

Question

Hi,
I'm writing an application that needs to handle different types of input file.
Each type of input file will be handled by a different processing class.
I plan to use a controller class that will read from a database rows that each contain a file name and processor class name such that the class can then be used to process that file:
So on a table somewhere I might have relationships like:
file1.csv , ProcessorClassA
file2.csv , ProcessorClassB
file3.csv , ProcessorClassB
My hope is that if I need a new processor class, I will not have to change the controller class. I simply write the new class say, ProcessorClassC and put an entry in my table for:
file4.csv , ProcessorClassC
So, finally, the question...
I can read in the new class name into a string but how can I employ that class or instantiate objects of that new class and use their methods.
The rationale is that so that the controller class needs no further modifications no matter how many new processor classes are required.
Any ideas anyone?

Answer 1

A factory class? I'm all ears... or is that another
days work...?Look e.g. here (or Google for "Factory Design Pattern"):
http://www.exciton.cs.rice.edu/JavaResources/DesignPatterns/FactoryPattern.htm